A main stream of zoom lenses of compact digital cameras currently available includes a type where the lens barrel collapses into the camera when the camera is not used. This type where the lens barrel collapses into the camera when the camera is not used has been proposed not only for a zoom lens, but also for a wide angle lens with a fixed focal point, of which focal length, with respect to an infinite object point, does not change (e.g. see Patent Document 1).